Direction-responsive control arrangement for reversible motors



gummi HIS ATTORNEY Patented Aug. 28, 195

DIRECTION-'RESPONSIVE CoNraoL lAR- -RANGEMENT Foa RlEv-ERSIBLE: MorroRs Kenneth M. Chappell, Round Lake,"fIll., assignor Ato Zenith Radio yGol-por Illinois ation, a corporation :of

ApplicationfMay 419, 195 0 ,Serial ."No. 163,060

(Cl. B18-'46.8

Y 310 Claims. `1

This invention relates to a direction-responsive control arrangement for a -reversible motor for maintaining energization thereof to effect rotation in a selected one -of two directions and through a preselected number oi complete or fractional revolutions. is useful in manyenvironments, it is especially vsuited for incorporation in motor-operated positioning systems Vof the step-by-step type which are utilized for actuating the tuningdevice of a Wave-signal receiver and it Will be described in that connection.

Aprior motor-driven positioning system of the stepping type includes one or moremotoractuated position-determining cams which operateswitchingmeans electrically connected ina relay circuitfor the motor. This circuitis com- Vprised of -an electro-mechanical relay device for ment to provide the selected-condition. lThis result is ineiiicient as compared with a bidirectional system which greatly facilitates the tuning operation. However, 'as ypointed out, `to 'achieve'bidirectionality in the previous arrangement additional lelements are required and production costs are consequently undesirably high.

It is an object of this invention, therefore, to provide a novel direction-responsive"-arrangement for a reversible motor Which-avoids vthe 'deciencies of the described prior system.

A further object of the invention is to provide a novel direction-responsive control arrangement for a reversible motor which is'entirely'e'iiicient in operation and yet is inexpensive to construct.

In accordance with the invention, a directionresponsive control arrangement for a reversible motor comprises a cam supported for movement along a predetermined path. The cam extends portions which denne cam surfaces.

has a pair of surfaces so positioned that one such surface engages one of the cam surfaces in re- -sponse to movement of the cam in one direction Although the inventionV the -cam in'the opposite direction. 'At least two o'f the aforementioned surfaces are inclined across the pathof movement 'of the camto defiectth'e 'follower relative to the path-and yina sense determined 'by the directi'on of movement 'of the cam. 'Meansareprovided V'ior mechani- "cally 'coupling the'cam vto the'motor 'at'leas'tidu-ring rintervals in 'which the motor is energized. The Vsystem further includes vone energizing circuit for themotor that'is vcompleted upon `deection of the follower lin one sense to maintain movement "of `the cam vand/'another energizing circuit for the motor that iscompleted upon deilection ofthe followenlnthe opposite vsense to maintain movement'of the Ycam, 'and means'a're provided for initially movingcthe 'cam lalon'g'its A,path ofmovement.

V`The features 'of thejpresent'invention Vwhich are 'believedto be'nove'lare set forth withparticularity in the appended claims. The present invention itself, both 'as to'its organization `and manner of operation, together Withifurtherjobjects and 'advantagesthereof may `best loe underistood by reference to the following description taken 'in .connection with the accompanying drawing in'which: l Figi is a plan'viewof a turretassem-blywhich includes. a direction-responsive 'controlarrangement constructed inaccordance with the invention;

Fig. 2 is an end'view ofthe assemblyshownpin shown includes a tub-like mounting structure' Il) provided with end plates'I I and I2. An elongated shaft I3 Vis rotatably Supportedby end plates. II and I2 andextends through the interior of structure ID andbeyond each of its end plates. A -.cylindrically shaped turret member I4 includes ,v a pair of .disc-'shaped end membersl and. I6

spaced. from one-another along. shaft I3 and ,supported for rotation therewith. YTurret Id'fu'rther includes av Vfamily of iiat strips ofV insulating Illa- 3 terial, individually extending between and connected at each end to the discs I5 and I6. Only strips I1 through 2l appear in Fig. 1 although it will be understood that any number, up to the maximum accommodated by discs I5 and I6, may be provided. These strips are identical in construction and usually support one or more tun- 'ing elements for each of the radio-frequency am- 29-30, 3I-32 and 33-34 supported on a strip 35 of insulating material secured to a side portion of structure I0. Of course, the tuning elements of each strip on the turret are preset su that the receiver is tuned to a. preselected opaV erating frequency, corresponding to a broadcast station or television channel as the case may be,

whenever the tuning-element contacts of any strip engage the stationary contacts of structure I0. Turret tuners of this type and their electrical association with the tunable stages of a superheterodyne receiver are well understood in the art, rendering a more detailed description thereof unnecessary.

The end plate I6 of turret I4 is provided with a concentric, annular cam surface 43 of hill and dale configuration having one dale or depression corresponding to each peripheral portion of the end plate to which a tuning strip may be affixed.

A leaf spring 44 is affixed at one extremity to end plate I2 of structure II] and carries at its opposite end a cam-engaging ball or detent member 45 biased into engagement with cam surface 43. There is thus provided an indexing system whereby turret I4 may be accurately oriented at any 4one of a plurality of selected positions in which the contact-making elements of a selected one of the stripsare in engagement with contacts 29-.34.

A spur gear 46 is fixed to the extremity of shaft ,Y I3 projecting beyond end plate I5 and is in meshing engagement with another spur gear 41 supported for rotation with a shaft 48. The shaft 48 is journaled for rotation at one end in a bracket 49 affixed to member II of structure I6 and the -other end is provided with a control knob 56. An-

other spur gear 5| is supported for rotation with shaft 48 in a position between gear 41 and knob 50 and is in driving engagement with a pinion 52 journaled for rotation on a stub shaft supported .by a bracket 53, in turn, aiixed to portion I I of structure Il). Gear 52 is in driving engagement with the inwardly extending teeth (not shown) of an internal gear housed within and mechanically coupled to a cylindrical member 55 supporte ed for rotation relative to shaft 48 and having an indicator scale inscribed on its outer periphery. The characters of this scale are preferably numbers designating the several tuning positions of the turret.

A fiber spur gear 56 is supported for rotation with shaft I3 near the right-hand extremity thereof (Fig. l) and a driving motor 51 mounted on member I0 by a bracket 58 is positioned so that the axis of its shaft 59 is in the plane of gear 56,

but does not intersect the gear proper. The shaft 59 carries a flexible shaft coupler `66 here shown as an elongated, cylindrical, resilient member. The other end of coupler 60 engages a worm shaft '6I carrying a worm gear 65 and journaled in spaced arms 62 and 63 of a carriage member 64. The carriage 64 is loosely mounted on la pair of studs 66 and 61 for movement in a direction perpendicular to shaft 5-9 of motor l5l and perpendicular to shaft I3. These studs project from a bracket 68 that is aiiixed to a plate 69 supported from portion I2 of unit IU. A leaf spring 18 is anchored at one end to stud 61 and its other end bears against the under side of carriage 64 to bias the carriage and worm 65 out of engagement with spur 56, the heads of studs 66 and 61 limiting upward movement of carriage 64.

An electro-magnet 1I is supported on an extension of bracket '6B with its pole piece facing carriage 64 and the carriage, being constructed of magnetic material, serves as the armature of the magnet. Therefore, when magnet rII is energized, the magnetic field produc-ed thereby is effective to attract carriage 64 toward the magnet and carry Aworm I65 from its inactive position to an operating position in driving engagement with spur gear 56. Consequently, spur gear 56, worm 65 and magnet 1I selectively permit a driving connection to be completed, coupling motor shaft 59 with turret shaft I3. Motor 5l preferably is of the split-field, reversible type so that turret shaft I3 may be power-operated in either of two rotational directions.

Referring now more particularly to the portions of the apparatus which, in accordance with the invention, provide a direction-responsive control arrangement for a reversible motor, a disc member 15 is secured to the end of shaft I3 that exten'ds beyond gear 56. The disc 15 includes a plurality of nat, tooth-like cams equi-spaced about its periphery, one cam being provided for each tuning-strip accommodation of turret I4. For convenience, however, only the cams 16, 11, 1-3 and 19 have been shown. Since the cams rotate with disc 15, they are supported for movement along a predetermined curvilinear or circular path. As more clearly shown in Fig. 3, each of the cams terminates in tapered, spaced edge portions which define cam surfaces. For example, with reference to Fig. 3a, cam 16 has edge portions W and X while cam 11 includes similar edge portions W' and X.

An S-shaped cam follower is supported at one end of a switch-actuating arm 8l of a resilient material, the other end of which is aflixed to a switch assembly 82. A mounting plate I82 adjustably supported on member 69 carries the assembly 82 so that it is adjustable relative to the path of movement of the cams of disc 15. Follower 88 is spring biased in a normal quiescent position in the path of movement of the tooth cams and includes a pair of end surfaces Y and Z inclined in the same sense across the path of movement of the cams. In the quiescent condition of the system, follower 80 is disposed in the gap between two successive cam teeth of disc 15.

The switch assembly 82 is of the single-pole, double-throw type and includes one pair of normally open contacts 83 positioned on one side of element y8I so that when follower 80 is displaced in a direction toward the contacts 83, an energizing circuit for driving motor 51 in one direction is closed through the contacts. A pair of normally open contacts 84 is positioned on the other side of element -BI and, when follower 80 is displaced in the opposite direction, the contacts 84 90 across winding 89.

field of electromagnet 1l displaces carriage .54

lcomplete another energizing circuit for driving motor 51 in the opposite direction.

With reference to Fig. 4, the electrical circuit connections for the arrangement are as follows:

The primary winding 85 of a step-down trans- 'capacitor 981 and winding 88 is connected to the xed contact of the normally open pair of contacts 83, the movable contact being returned to the remaining terminal of secondary 81 of transformer BB. The junction of capacitor 98 and winding 89 is connected to the fixed contact of normally open contact pair 84 and the movable contact thereof is connected with the movable contact of switch 83. Conductors 9i, 92 and 93 connect switch 82 in parallel with another singlepole double-throw switch 94 which may be remote from the mechanism under consideration Vand is provided to permit remote control of the tuning.

Since electromagnet 1i is in series with the windings of motor 51, Whenever the motor is energized the electromagnet is energized. This completes a driving connection to shaft I3 and all the rotatable components of the tuning mechanism during operating intervals in which the motor is energized.

In operation, the described motor-driven tuning system effects step-by-step rotational displacement of turret I4 in a selected direction to bring any particular one of the tuning strips into operative relation with the reeciver through the engagement of the terminals of tuning elements With the stationary terminals 29-34. The direction of rotation is usually chosen to bring the v particular tuning strip into operative position as quickly as possible and the movement of the turret from one strip to the next is accomplished by the driving motor once its energizing circuit has been completed. The motor circuit may be established in either of two ways, by manual rotation of the control knob 5I) or by actuation of the remote-control switch 94. For convenience, the control of the motor will be considered initially on the assumption that control knob 59 is manually operated to accomplish tuning.

Let it be assumed that knob 5D is rotated to effect initial rotation of the turret I4 and the disc in the direction represented by arrow 95 in Figs. 2 and 3. Cam 16 is displaced from its position in Fig. 3a toward follower 80 and surface X of the cam engages surface Y of the fol-,f

lower. Since surface Y is inclined to the path of movement of cam 16, follower 8U is displaced transversely to this path as indicated by arrow 98, and contacts 84 are closed (Fig. l) The closing of contacts 84 completes an electrical circuit from secondary 81 of transformer 85 through electromagnet 1I and winding 89 of motor 51 and winding 88 is connected in series with condenser The resulting magnetic downwardly to bring worm 65 into driving engagement with spur gear 56 simultaneously with the energization of motor 51. The circuit connections to the motor are such that rotation of the turret and the associated elements continues '6 in the initial direction. Follower 80 is maintained in its deflected condition by engagement with the fiat side of cam 16. The circuit is opened when the cam clears the follower which is then returned to its normal condition by the bias of arm 8i.

`The cams and follower 80 are so positioned that the motor and relay circuits are deenergized just before the turret reaches its indexed position whereupon, the bias of spring 44 acting upon detent 45 drives the turret further to its horned or detent-indexed position. The turret thus comes to rest at one step removed from its initial position. It will be observed that even if the motor circuit is shut off slightly beyond the required position of the turret the bias of spring 44 in cooperation with detent 45 and the annular cam l43 effects a mechanical displacement in the opposite direction to bring the turret to indexed position.

Assume now that the knob 50 is rotated initially in the direction opposite to that of the above example to carry the turret and disc in the reverse direction. The cams are displaced from the position shown in Fig. 3a in the direction represented by arrow 91 in Fig. 3c and as a result follower 80 is displaced in the direction of arrow 98 which is opposite to the'displacement of the prior example. This movement of follower 80 causes contacts 83 to be closed and the electromagnet 1| and the motor 51 are energized. The energizing circuit for the motor provides reverse rotation from that of the preceding example and the motor drives the turret in the manually initiated direction. As is the case for the example of Fig. 3b, the circuit is opened when the cam no longer maintains the follower in deflected condition. For this illustration the circuit shut-off rfeature may be better understood from an observation of Fig. 3d. Inasmuch as the extremity of follower 80 that is engaged with surface X of cam 11 is freed thereof with but a smalldisplacement of cam 11 from the position shown, the follower -80 quickly returns to a quiescent position.

Each of the afore-described conditions may be produced by the operation of remote switch 94. If the movable arm of this switch is displaced into engagement with either one of the xed contacts, one of the two energizing circuits for the motor is completed. Contact need be to a position wherein one of the cams deilects follower 88 and the circuit is sealed in the manner described in connection with the use of knob Rotation continues until the next indexed position for the turret is obtained.

For step-by-step operation the remote switch is closed for but a moment. However, if the switch is held in a closed condition, the motor continuously drives the turret. When the switch is opened, if the follower 89 is 'between successive cams, the motor stops but if the follower is in a deflected condition, rotation continues until an indexed position is attained.

The invention thus provides a novel step-bystep direction-responsive control arrangement for a reversible motor which avoids the inefficiency of a unidirectional system. Moreover, the direction-responsive control arrangement, although entirely eiiicient in operation, is less expensive to construct than a system in which a group of electromechanical relays is required.

While a particular embodiment of the present Ainvention has been shown and described, it will be obvious to those skilled in the art that vchanges and modifications may be made without departing from thisinvenuon in its broader pects, and, therefore, the aim in ,theappended claims is to cover all such .changes and modicaf tions as fall within the true spiritand scope of `this invention.

I claim: 1. A direction-responsive control arrangement fora reversible motor comprising: ac amAV supported for movement along a predetermined path, extending along said path, and terminatfing in spaced edgel portions definingvv cam surfaces; a cam follower vhaving a pair of surfaces so positioned that one suchsurface engages one of, said cam surfaces in response to movement of Vsaid Ycam in oneV direction .while thepotherlsuch surface engages'the other of said camsurfaces -in response to movementof said cam in the op,- vposite direction, at leastV two of said surfaces being inclined across said path to deflect said -Afollower relative to said path and in a sense determined by the direction of movement of Asaid l cam; means for mechanically coupling said cam to said motor at least during intervals in which ,Y said motor is energized; one energizing circuit for said motor completed upon deflection ofgsaid follower inone sense to maintain movementof said cam; anotherenergizing circuitfor said motor completed upon deection of said follower in the opposite sense to maintain movement of said cam; and means for initially moving saidv cam along said path.y

2. A direction-responsive control arrangement for a reversible motor comprising: a plurality of cams supported for movement along` a predetermined path, successively and equally spaced from one another along said path, and each eX- vtending along said path and terminating in spaced edge portions defining cam surfacesyia cam follower having a pair of surfaces so positioned that one such surface engages one of said cam surfaces in response to movement of said cams in one direction while the other suchsurface engages the other of said cam surfaces in response to movement of said cams in the opposite direction, at least two of said surfaces being in- `clined across said path to deflect said follower relative to said path and in a sense determined by the direction of movement of said cams; means for mechanically coupling said cams to said motor at least during intervals in which said motor is energized; one energizing circuit for said motor completed upon deection of said i follower in one sense to maintain movement of i said cams; another energizing circuit for said motor completed upon deflection of said follower in the opposite sense to maintain movement of said cams; and means for initially movingsaid I@cams along said path.

3. A direction-responsive control arrangement for a reversible motor comprising: a disc mem-v 'ber including a plurality of tooth-like cams supported at the periphery thereof for movement therewith along a curvilinear path, successively and equally spaced from one another along said path, and each extending along said path terminating in spaced edge portions defining cam surfaces; a cam follower having a pair of and surfaces so positioned that one such surface engages one of said cam surfaces in response to movement of said cams in one direction while the other such surface engages the other of said cam surfaces in response to movement of said cams in the opposite direction, at least two of il' said surfaces being inclined across said path to deflect said follower relative to said path and in -a sense determined by the direction of movement of said cams; means for mechanically coupling said disc member to said'motor at least during intervals inwhich said motor is energized; one energizing circuit for said motor completed upon deflection of said follower in one sense to main- `tain movement of said cams; another energizing circuit for said motor completed upon deflection lof said follower in the opposite sense to maintain movement of said cams; and means for initially moving said cams along said path. l

. v 4. A direction-responsive control arrangement for a reversible motor comprising: a cam supported for vmovement along a predetermined path, extending along said path, and terminatng in spaced edge portions defining cam surfaces; a cam followed positioned in said path and .having a pair of surfaces inclined in the same gsense across said path, each of said surfaces be- Aing engageable by a respective one of said cam `ing said cam along said path.

5. A direction-responsive control arrangement for a reversible motor comprising: a cam supported for movement along a predetermined path, extending along said path", and terminating in spaced edge portions defining cam surfaces; an S-shaped cam followed positionedrin said path and having a pair of end surfaces inclined in the same sense across said path, each of said surfaces being engageable by a a respective one of said cam surfaces in response to movement of said cam to deflect said follower relative to said path and in a sense determined by the direction of movement of said cam; means for mechanically coupling said cam to said motor at least during intervals in which said motor is energized; one energizing circuit for said motor completed upon deflection of said follower in one sense to maintain movement of said cam;

- another energizing circuit for said motor completed upon deflection of said follower in the opposite sense to maintain movement of said cam; and means for initially moving said cam along said path.

6. A direction-responsive control arrangement for a reversible motor comprising: a disc member including a plurality of ilat, tooth-like cams supported at the periphery thereof for movee ment therewith along a curvilinear path, successively and equally spaced from one another along said path, and each extending along said Y path and terminating in tapered spaced edge portions defining cam surfaces; a cam follower spring biased in a normal position in said path yand having a pair vof surfaces inclined in the 1 same sense across said path, each of said surfaces being engageable by a respective one of said cam surfaces in response to movement of said cams to deflect said follower relative to said path and in a sense determined by the direction m-of movement of said cams, said follower being maintainable in deflected condition by engagement with the ilat portion lof that .cam which effects such deflection; means for mechanically coupling said disc member to said motor at least during intervals in which said motor is energized; one energizing circuit for said motor completed upon deflection of said follower in one sense to maintain movement of said cams; another energizing circuit for said motor completed upon deflection of said follower in the opposite sense to maintain movement of said cams; and means for initially moving said cams along said path.

7. A direction-responsive control arrangement for a reversible motor for driving a shaft to a predetermined angular position comprising: a cam coupled to said shaft and supported for movement along a predetermined path in response to movement of said shaft, said cam extending along said path and terminating in spaced edge portions defining cam surfaces; a cam follower having a pair of surfaces so positioned that one such surface engages one of said cam surfaces in response to movement of said cam in one direction while the other such surface engages the other of said cam surfaces in response to movement of said cam in the opposite direction, at least two of said surfaces being inclined across said path to deiiect said follower relative to said path in a sense determined by the direction of movement of said cam; means for mechanically coupling said shaft to said motor at least during intervals in which said motor is energized; one energizing circuit for said motor completed upon deflection of said follower in one sense to maintain movement of said cam; another energizing circuit for said motor completed upon deflection of said follower in the opposite sense to maintain movement of said cam; and manual means for initially moving said cam along said path into engagement with said follower.

8. A direction-responsive control arrangement for a reversible motor comprising: a cam supported for movement along a vpredetermined path, extending along said path, and terminating in spaced edge portions defining cam surfaces; a cam follower having a pair of surfaces so positioned that one such surface engages one of said cam surfaces in response to movement of said cam in one direction while the other such surface engages the other of said cam surfaces in response to movement of said cam in the opposite direction, at least two of said surfaces being inclined across said .path to deflect said follower relative to said path and in a sense determined by the direction of movement of said cam; means for mechanically coupling said cam to said motor at least during intervals in which said motor is energized; one energizing circuit for said motor completed upon deflection of said follower in one sense to maintain movement of said cam; another energizing circuit for said motor completed upon deflection of said follower in the opposite sense tc maintain movement of said cam; and a remote-control switching circuit for initially energizing said motor to move said cam along said path into engagement with said follower.

l0 9. A direction-responsive control arrangement for a reversible motor for driving a shaft to a predetermined angular position comprising: a cam coupled to said shaft and supported for movement along a predetermined path in response to movement of said shaft, said cam extending along said path and terminating in spaced edge portions dening cam surfaces; a cam follower having a Ipair of surfaces so positioned that one such surface engages one of said cam surfaces in response to movement of said cam in one direction while the other such surface engages the other of said cam surfaces in response to movement of said cam in the opposite direction, at least two of said surfaces being inclined across said path to deflect said follower relative to said path in a sense determined `by the direction ofv movement of said cam; a worm and spur gear for mechanically coupling said shaft to said motor but normally maintained out of coupling engagement with one another; means for engaging said worm and said gear during operating intervals in which said motor is energized; one energizing circuit for said motor completed upon deflection of said follower in one sense to maintain movement of said cam; another energizing circuit for said motor completed upon deflection of said follower in the opposite sense to maintain movement of said cam; and means for initially moving said cam along said path.

10. A direction-responsive control arrangement for a reversible motor for driving a shaft to a predetermined angular position comprising: a plurality of cams supported for movement along a predetermined path, successively and equally spaced from one another along said path, and each extending along said path and terminating in spaced edge portions defining cam surfaces; a cam follower having a pair of surfaces so positioned that one such surface engages one of said cam surfaces in response to movement of said cams in one direction while the other such surface engages the other of said cam surfaces in response to movement of said cams in the opposite direction, at least two of said surfaces being inclined across said path to deflect said follower relative to said path in a sense determined by the direction of movement of said cams; a worm and spur gear for mechanically coupling said shaft to said motor but normally maintained out of coupling engagement with one another; means for engaging said worm and said gear during operating intervals in which said motor is energized; one energizing circuit for said motor completed upon deflection of said follower in one sense to maintain movement of said cams; another energizing circuit for said motor completed upon deflection of said follower in the opposite sense to maintain movement of said cams; a detent mechanism associated with said shaft for homing said shaft to an indexed position when said cam follower is positioned between successive ones of said cams; and means for initially moving said cams along said path.

KENNETH M. CHAPPELL.

No references cited. 

